1. Field of the Invention
This invention relates to a method for the pattern-processing of a photosensitive resin composition for obtaining a scum-free, high-resolution pattern.
2. Prior Art
In a semiconductor industry, a photosensitive resin such as a photoresist, a photosensitive polyimide or the like has recently been often used in the preparation of a very fine circuit such as IC, LSI or the like or as an insulating film or protective film in a package requiring processing. The characteristic feature of the photosensitive resin consists in that a high precision resin pattern can be obtained by a relatively simple apparatus. In particular, a positive photoresist comprising as a base a phenol novolak resin using a diazoquinone or the like as a photosensitive agent enables the formation of a pattern excellent in resolution because it does not swell during developing. In addition, since the developer is an alkaline aqueous solution, the positive photoresist is excellent in an aspect of safety. As discussed above, the photosensitive resin has many features, and hence, has been often used in the production of fine circuits and the like of the above semiconductor. On the other hand, in a photosensitive, heat-resistant resin such as a photosensitive polyimide which is used in the insulating film or protective film of a semiconductor, a positive type photosensitive, heat resistant resin having such features as high resolution, environmental pollution-free developer and the like has been developed similarly to the photoresist (see, for example, JP-A-64-60630, JP-B-1-46862 and the like) and has attracted attention as a resin for insulating film or protective film of a highly integrated semiconductor.
Most of the positive photosensitive resin compositions are composed of a combination of an alkali soluble polymer with the above-mentioned diazoquinone compound as a photosensitive agent. In the unexposed portions, these quinonediazide compounds are insoluble in an alkaline aqueous solution; however, upon exposure, they cause a chemical reaction to become soluble in an alkaline aqueous solution. Accordingly, utilizing the difference in solubility between the exposed portion and the unexposed portion, the exposed portion is removed by an alkaline aqueous solution, whereby it becomes possible to prepare a coating film pattern composed of only the unexposed portion.
The alkaline aqueous solution used as a developer is generally an aqueous solution of tetramethylammonium hydroxide (referred to hereinafter as TMAH). When a photoresist comprising as a base a conventional phenol novolak resin is developed, a good development can be effected using an aqueous solution of this TMAH. However, in the case of a photosensitive resin composition comprising a polybenzoxazole precursor as stated in JP-B-1-46862 as a base, there is such a disadvantage that an undeveloped portion (scum) remains in the exposed portion which should be completely removed to avoid deterioration of the resolution.